faster collisions

Squashed commit of the following:

commit 053c06ea29702728e2605899a2b47edac647c459
Author: Alvie Rahman <alvierahman90@gmail.com>
Date:   Sat Dec 3 16:09:51 2022 +0000

    begin documentation on codebase: sprite metadata

commit 435f0c62743112818594f4b1a902d90d1f60823a
Author: Alvie Rahman <alvierahman90@gmail.com>
Date:   Sat Dec 3 16:05:37 2022 +0000

    formatting, mostly

commit f338476aaf4c33081969b18b2a6d13a3639571cd
Author: Alvie Rahman <alvierahman90@gmail.com>
Date:   Fri Dec 2 23:18:27 2022 +0000

    way faster collisions

docs/res/sprites_metadata.c.txt

@@ -0,0 +1,9 @@
+sprite.c:
+
+struct Sprites
+
+collision_offset = {
+	quad1x1, quad1y1, quad1x2, quad1y2,
+	quad2x1, quad2y1, quad2x2, quad2y2,
+	quad3x1, quad3y1, quad3x2, quad3y2
+}

readme.md

@@ -16,3 +16,10 @@ make all
 ```
 
 the gameboy rom will be output to `obj/untitled2dshooter.gb`
+
+
+## credits
+
+### art
+
+a cool guy named louie - drew mike

res/sprite_metadata.c

@@ -0,0 +1,186 @@
+#include <gb/gb.h>
+#include "../src/sprite.h"
+#include "../src/flags.h"
+
+Sprite sprites_info[] = {
+	{
+		.frames_since_last_dash = 0,
+		.frames_since_last_jump = 0,
+		.name = "arrow",
+		.has_diag_sprites = 0,
+		.bitmap_index = SI_LEFT,
+		.has_joypad = 0,
+		.pos = { .x = 0, .y = 0},
+		.vel = { .x = 0, .y = 0},
+		.acc = { .x = 0, .y = 0},
+
+		.bitmap_indexes[SI_UP] = 12, .bitmap_prop[SI_UP] = 0,
+			.collision_offset[SI_UP] = {
+				3,   8,   1,   7,
+				255, 255, 255, 255,
+				255, 255, 255, 255
+			},
+		.bitmap_indexes[SI_DOWN] = 12, .bitmap_prop[SI_DOWN] = S_FLIPY,
+			.collision_offset[SI_DOWN] = {
+				3,   2,   1,   1,
+				255, 255, 255, 255,
+				255, 255, 255, 255
+			},
+		.bitmap_indexes[SI_LEFT] = 11, .bitmap_prop[SI_LEFT] = 0,
+			.collision_offset[SI_LEFT] = {
+				8,   3,   7,   1,
+				255, 255, 255, 255,
+				255, 255, 255, 255
+			},
+		.bitmap_indexes[SI_RIGHT] = 11, .bitmap_prop[SI_RIGHT] = S_FLIPX,
+			.collision_offset[SI_RIGHT] = {
+				2,   3,   1,   1,
+				255, 255, 255, 255,
+				255, 255, 255, 255
+			},
+		.bitmap_indexes[SI_UP_RIGHT] = 13, .bitmap_prop[SI_UP_RIGHT] = 0,
+			.collision_offset[SI_UP_RIGHT] = {
+				2,   8,   1,   7,
+				255, 255, 255, 255,
+				255, 255, 255, 255
+			},
+		.bitmap_indexes[SI_UP_LEFT] = 13, .bitmap_prop[SI_UP_LEFT] = S_FLIPX,
+			.collision_offset[SI_UP_LEFT] = {
+				8,   8,   7,   7,
+				255, 255, 255, 255,
+				255, 255, 255, 255
+			},
+		.bitmap_indexes[SI_DOWN_LEFT] = 13, .bitmap_prop[SI_DOWN_LEFT] = S_FLIPX | S_FLIPY,
+			.collision_offset[SI_DOWN_LEFT] = {
+				8,   2,   7,   1,
+				255, 255, 255, 255,
+				255, 255, 255, 255
+			},
+		.bitmap_indexes[SI_DOWN_RIGHT] = 13, .bitmap_prop[SI_DOWN_RIGHT] = S_FLIPY,
+			.collision_offset[SI_DOWN_RIGHT] = {
+				2,   2,   1,   1,
+				255, 255, 255, 255,
+				255, 255, 255, 255
+			}
+	},
+	{
+		.frames_since_last_dash = 0,
+		.frames_since_last_jump = 0,
+		.name = "dodgy_hat_guy",
+		.has_diag_sprites = 0,
+		.bitmap_index = SI_LEFT,
+		.has_joypad = 0,
+		.pos = { .x = 0, .y = 0},
+		.vel = { .x = 0, .y = 0},
+		.acc = { .x = 0, .y = 0},
+
+		.bitmap_indexes[SI_UP] = 14, .bitmap_prop[SI_UP] = 0,
+			.collision_offset[SI_UP] = {
+				8,8, 1,1,
+				255, 255, 255, 255,
+				255, 255, 255, 255
+			},
+		.bitmap_indexes[SI_DOWN] = 15, .bitmap_prop[SI_DOWN] = 0,
+			.collision_offset[SI_DOWN] = {
+				8,8, 1,1,
+				255, 255, 255, 255,
+				255, 255, 255, 255
+			},
+		.bitmap_indexes[SI_LEFT] = 14, .bitmap_prop[SI_LEFT] = 0,
+			.collision_offset[SI_LEFT] = {
+				8,8, 1,1,
+				255, 255, 255, 255,
+				255, 255, 255, 255
+			},
+		.bitmap_indexes[SI_RIGHT] = 14, .bitmap_prop[SI_RIGHT] = S_FLIPX,
+			.collision_offset[SI_RIGHT] = {
+				8,8, 1,1,
+				255, 255, 255, 255,
+				255, 255, 255, 255
+			},
+		.bitmap_indexes[SI_UP_RIGHT] = 14, .bitmap_prop[SI_UP_RIGHT] = 0,
+			.collision_offset[SI_UP_RIGHT] = {
+				8,8, 1,1,
+				255, 255, 255, 255,
+				255, 255, 255, 255
+			},
+		.bitmap_indexes[SI_UP_LEFT] = 14, .bitmap_prop[SI_UP_LEFT] = S_FLIPX,
+			.collision_offset[SI_UP_LEFT] = {
+				8,8, 1,1,
+				255, 255, 255, 255,
+				255, 255, 255, 255
+			},
+		.bitmap_indexes[SI_DOWN_LEFT] = 15, .bitmap_prop[SI_DOWN_LEFT] = 0,
+			.collision_offset[SI_DOWN_LEFT] = {
+				8,8, 1,1,
+				255, 255, 255, 255,
+				255, 255, 255, 255
+			},
+		.bitmap_indexes[SI_DOWN_RIGHT] = 15, .bitmap_prop[SI_DOWN_RIGHT] = S_FLIPX,
+			.collision_offset[SI_DOWN_RIGHT] = {
+				8,8, 1,1,
+				255, 255, 255, 255,
+				255, 255, 255, 255
+			}
+	},
+	{
+		.frames_since_last_dash = 0,
+		.frames_since_last_jump = 0,
+		.name = "mike",
+		.has_diag_sprites = 0,
+		.bitmap_index = SI_LEFT,
+		.has_joypad = 0,
+		.pos = { .x = 0, .y = 0},
+		.vel = { .x = 0, .y = 0},
+		.acc = { .x = 0, .y = 0},
+
+		.bitmap_indexes[SI_UP] = 25, .bitmap_prop[SI_UP] = 0,
+			.collision_offset[SI_UP] = {
+				8,8, 1,1,
+				255, 255, 255, 255,
+				255, 255, 255, 255
+			},
+		.bitmap_indexes[SI_DOWN] = 22, .bitmap_prop[SI_DOWN] = 0,
+			.collision_offset[SI_DOWN] = {
+				8,8, 1,1,
+				255, 255, 255, 255,
+				255, 255, 255, 255
+			},
+		.bitmap_indexes[SI_LEFT] = 21, .bitmap_prop[SI_LEFT] = 0,
+			.collision_offset[SI_LEFT] = {
+				8,5, 1,1,
+				255, 255, 255, 255,
+				255, 255, 255, 255
+			},
+		.bitmap_indexes[SI_RIGHT] = 21, .bitmap_prop[SI_RIGHT] = S_FLIPX,
+			.collision_offset[SI_RIGHT] = {
+				8,5, 1,1,
+				255, 255, 255, 255,
+				255, 255, 255, 255
+			},
+		.bitmap_indexes[SI_UP_RIGHT] = 23, .bitmap_prop[SI_UP_RIGHT] = 0,
+			.collision_offset[SI_UP_RIGHT] = {
+				8,8, 1,1,
+				255, 255, 255, 255,
+				255, 255, 255, 255
+			},
+		.bitmap_indexes[SI_UP_LEFT] = 23, .bitmap_prop[SI_UP_LEFT] = S_FLIPX,
+			.collision_offset[SI_UP_LEFT] = {
+				8,8, 1,1,
+				255, 255, 255, 255,
+				255, 255, 255, 255
+			},
+		.bitmap_indexes[SI_DOWN_LEFT] = 24, .bitmap_prop[SI_DOWN_LEFT] = S_FLIPX,
+			.collision_offset[SI_DOWN_LEFT] = {
+				8,7, 1,1,
+				255, 255, 255, 255,
+				255, 255, 255, 255
+			},
+		.bitmap_indexes[SI_DOWN_RIGHT] = 24, .bitmap_prop[SI_DOWN_RIGHT] = 0,
+			.collision_offset[SI_DOWN_RIGHT] = {
+				8,7, 1,1,
+				255, 255, 255, 255,
+				255, 255, 255, 255
+			}
+	}
+};

res/sprite_metadata.h

@@ -0,0 +1,3 @@
+#include "../src/sprite.h"
+
+extern Sprite sprites_info[];

res/sprites.c

@@ -10,7 +10,7 @@
   Compression          : None.
   Counter              : None.
   Tile size            : 8 x 8
-  Tiles                : 0 to 10
+  Tiles                : 0 to 25
 
   Palette colors       : None.
   SGB Palette          : None.
@@ -25,8 +25,8 @@
 /* Start of tile array. */
 unsigned char sprites[] =
 {
-  0xF7,0x08,0xED,0x12,0xFE,0x11,0xFF,0x38,
-  0xFE,0x39,0xFE,0x39,0xFF,0x7E,0xFF,0x6E,
+  0xFF,0x19,0xEF,0x17,0xFF,0x11,0xFF,0x3B,
+  0xFE,0x3F,0xFE,0x3D,0xFF,0x7E,0xFF,0x6E,
   0xFF,0x00,0xC3,0x42,0x81,0x00,0x81,0x00,
   0x81,0x00,0x81,0x00,0xC3,0x42,0xFF,0x00,
   0xC3,0xC3,0xDB,0xDB,0x3C,0x3C,0x7E,0x7E,
@@ -46,7 +46,37 @@ unsigned char sprites[] =
   0xC3,0xC3,0xDB,0xDB,0x3C,0x3C,0x7E,0x7E,
   0x7E,0x7E,0x3C,0x3C,0xDB,0xDB,0x42,0xC3,
   0x43,0xC3,0xDB,0xDB,0x3C,0x3C,0x7E,0x7E,
-  0x7E,0x7E,0x3C,0x3C,0xDB,0xDB,0x43,0xC3
+  0x7E,0x7E,0x3C,0x3C,0xDB,0xDB,0x43,0xC3,
+  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
+  0x00,0x00,0x00,0x43,0x38,0xC6,0x00,0x43,
+  0x00,0x02,0x00,0x07,0x02,0x00,0x02,0x00,
+  0x02,0x00,0x00,0x02,0x00,0x07,0x00,0x05,
+  0x00,0x03,0x02,0x01,0x04,0x00,0x08,0x00,
+  0x00,0x30,0x00,0x50,0x00,0x20,0x00,0x00,
+  0x38,0x38,0x7C,0x7C,0x7C,0x44,0x38,0x00,
+  0x18,0x00,0x18,0x18,0xBD,0xBD,0xBD,0xBD,
+  0x38,0x38,0x7C,0x7C,0x7C,0x44,0x39,0x01,
+  0x99,0x81,0x98,0x98,0x3C,0x3C,0x3C,0x3C,
+  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
+  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
+  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
+  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
+  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
+  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
+  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
+  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
+  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x7E,
+  0x25,0xFE,0x18,0xE7,0x7E,0xFF,0x00,0xDB,
+  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x7C,
+  0x38,0xEE,0x52,0xAD,0x7C,0xFF,0x01,0xD7,
+  0x00,0x38,0x10,0x6E,0x2C,0x77,0x22,0xDD,
+  0x7E,0xFF,0x12,0xC9,0x18,0xE7,0x00,0x7E,
+  0x00,0x38,0x10,0x6C,0x3C,0xC6,0x60,0xBF,
+  0x0E,0xFF,0x78,0xF3,0x00,0xDE,0x00,0x70,
+  0x00,0x00,0x30,0x4C,0x70,0x9E,0x06,0xFB,
+  0x7C,0xF3,0x0E,0x5F,0x00,0x7B,0x00,0x1E,
+  0x00,0x7E,0x18,0xE7,0x36,0xED,0x02,0xFD,
+  0x7E,0xFF,0x08,0x53,0x10,0x6E,0x00,0x38
 };
 
 /* End of SPRITES.C */

res/sprites.h

@@ -10,7 +10,7 @@
   Compression          : None.
   Counter              : None.
   Tile size            : 8 x 8
-  Tiles                : 0 to 10
+  Tiles                : 0 to 25
 
   Palette colors       : None.
   SGB Palette          : None.

res/tiles.c

@@ -25,8 +25,8 @@
 /* Start of tile array. */
 unsigned char tiles[] =
 {
-  0x10,0x00,0x00,0x00,0x08,0x00,0x10,0x00,
-  0x30,0x00,0x20,0x00,0x60,0x00,0x50,0x20,
+  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
+  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
   0xFF,0xFF,0xFF,0xFF,0x00,0xFF,0x00,0xFF,
   0x00,0xFF,0x00,0xFF,0x00,0xFF,0x00,0xFF,
   0x00,0xFF,0x00,0xFF,0x00,0xFF,0x00,0xFF,

src/constants.h

@@ -4,15 +4,15 @@
 #define MAX_PLAYER_COUNT 1
 
 #define GRAV_ACC 1
-#define TERM_VELY 3
+#define TERM_VELY 2
 #define TERM_VELX 2
-#define TERM_VELY_DIVISOR 3
+#define TERM_VELY_DIVISOR 5
 #define TERM_VELX_DIVISOR 3
 
 #define JUMP_VEL 4
 #define JUMP_TIMEOUT_FRAMES 18
 
-#define DASH_VELL 7
+#define DASH_VELL 4
 // mfw when pythagoras irl :scream_cat:
 #define DASH_VELD 5
 #define DASH_TIMEOUT_FRAMES 30

src/flags.h

@@ -24,6 +24,15 @@
 #define SC_IBL 0b0010
 #define SC_IBR 0b0001
 
+#define SI_UP         0
+#define SI_DOWN       1
+#define SI_LEFT       2
+#define SI_RIGHT      3
+#define SI_UP_RIGHT   4
+#define SI_DOWN_RIGHT 5
+#define SI_UP_LEFT    6
+#define SI_DOWN_LEFT  7
+
 /* Sprite Collision point diagram:
  *      x TL    LT x
  *      ------------

src/main.c

@@ -1,22 +1,25 @@
 #include <gb/gb.h>
+#include <gb/drawing.h>
 #include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
 #include "../res/tiles.h"
 #include "../res/map.h"
 #include"../res/sprites.h"
+#include"../res/sprite_metadata.h"
 #include "./flags.h"
 #include "./constants.h"
 #include "./sprite.h"
 #include "./vec.h"
 
+#define NO_SCREEN_SPRITES 6
+
 void init_gfx()
 {
 	// Load Background tiles and then map
 	set_bkg_data(0, 23, tiles);
 	set_bkg_tiles(0, 0, map.width, map.height, map.data);
-
-	set_sprite_data(0, 11, sprites);
-	set_sprite_tile(0, 2);
-	set_sprite_prop(0, 0);
+	set_sprite_data(0, 26, sprites);
 
 	// Turn the background map on to make it visible
 	SHOW_BKG;
@@ -25,25 +28,34 @@ void init_gfx()
 
 void main(void)
 {
-	unsigned int fc = 0;
-	struct Sprites sprite;
-
 	init_gfx();
 
-	sprite.pos.x = 72;
-	sprite.pos.y = 36;
-	sprite.vel.x = 0;
-	sprite.vel.y = 0;
-	sprite.acc.x = 0;
-	sprite.acc.y = 0;
-	move_sprite(0, sprite.pos.x, sprite.pos.y);
+	unsigned int i, jp, fc = 0;
+	struct Sprites screen_sprites[NO_SCREEN_SPRITES];
+
+
+	memcpy(&(screen_sprites[0]), &(sprites_info[2]), sizeof(Sprite));
+	memcpy(&(screen_sprites[1]), &(sprites_info[1]), sizeof(Sprite));
+	for (i = 2; i < NO_SCREEN_SPRITES; i++) memcpy(&(screen_sprites[i]), &(sprites_info[0]), sizeof(Sprite));
+
+	screen_sprites[4].has_joypad = 1;
+
+	for (i = 0; i < NO_SCREEN_SPRITES; i++) {
+		screen_sprites[i].bitmap_index_prev = -1;
+		screen_sprites[i].gb_sprite_index = i;
+		screen_sprites[i].pos.x = 72+(8*i);
+		screen_sprites[i].pos.y = 36+(8*i);
+		sprite_draw_to_screen(&(screen_sprites[i]));
+	}
 
 
 	// Loop forever
 	while(1) {
 		fc++;
-		sprite_iter_frame(&sprite, &map, joypad(), &fc);
-		move_sprite(0, sprite.pos.x, sprite.pos.y);
+		jp = joypad();
+		for (i = 0; i < NO_SCREEN_SPRITES; i++) {
+			sprite_iter_frame(&(screen_sprites[i]), &map, screen_sprites[i].has_joypad ? jp : 0, &fc);
+		}
 
 		// Done processing, yield CPU and wait for start of next frame
 		wait_vbl_done();

src/sprite.c

@@ -1,63 +1,45 @@
 #include <gb/gb.h>
 #include <stdlib.h>
+#include <stdio.h>
 #include "./vec.h"
 #include "./constants.h"
 #include "./flags.h"
 #include "./map.h"
 
 
+#define LYO 8
+#define GET_TILE_INDEX_BY_COORD(x, y)	((((y) / PIXELS_PER_TILE) * 20) + ((x) / PIXELS_PER_TILE))
+
 typedef struct Sprites {
+	int gb_sprite_index;
 	int frames_since_last_dash;
 	int frames_since_last_jump;
-	int size;
+	int bitmap_index_prev;
+	int bitmap_index;
+	int bitmap_indexes[8];
+	int bitmap_prop[8];
+	int has_diag_sprites;
+	int has_joypad;
+	char name[20];
+	int collision_offset[8][12];
 	UVec pos;
 	Vec vel;
 	Vec acc;
 } Sprite;
 
 
-typedef struct SpriteCorners {
-	UVec itl;
-	UVec itr;
-	UVec ibl;
-	UVec ibr;
-} SpriteCorners;
-
-
-int get_tile_index_by_coord(unsigned int x, unsigned int y);
-void getSpriteCorners(Sprite *sprite, SpriteCorners *r);
 void sprite_iter_frame(Sprite *sprite, Map *map, int joypad, unsigned int *fc);
-unsigned int sprite_internal_collision(Map *map, Sprite *sprite);
-unsigned int sprite_collision(Map *map, Sprite *sprite);
-
-
-int get_tile_index_by_coord(unsigned int x, unsigned int y)
-{
-	return ((y / PIXELS_PER_TILE) * 20) + (x / PIXELS_PER_TILE);
-}
-
-
-void getSpriteCorners(Sprite *sprite, SpriteCorners *sc)
-{
-	sc->itl.x = sprite->pos.x-8;
-	sc->itl.y = sprite->pos.y-16;
-	sc->itr.x = sprite->pos.x-1;
-	sc->itr.y = sprite->pos.y-16;
-	sc->ibl.x = sprite->pos.x-8;
-	sc->ibl.y = sprite->pos.y-9 ;
-	sc->ibr.x = sprite->pos.x-1;
-	sc->ibr.y = sprite->pos.y-9;
-}
+void sprite_draw_to_screen(Sprite *sprite);
+void sprite_update_bitmap(Sprite *sprite);
 
 
 // update a sprite for stuff that changes every frame
 void sprite_iter_frame(Sprite *sprite, Map *map, int joypad, unsigned int *fc)
 {
-	int c, collision_check_steps;
+	unsigned int colx, coly;
+	UVec original_position;
 
 	// target displacement is sprite->vel but may collide, giving actual displacment
-	Vec displacement = {.x = 0, .y = 0};
-	UVec original_position;
 
 	if (sprite->frames_since_last_jump <= JUMP_TIMEOUT_FRAMES) sprite->frames_since_last_jump++;
 	if (sprite->frames_since_last_dash <= DASH_TIMEOUT_FRAMES) sprite->frames_since_last_dash++;
@@ -108,74 +90,84 @@ void sprite_iter_frame(Sprite *sprite, Map *map, int joypad, unsigned int *fc)
 	// slow down sprite in kind of realistic way
 	// (in real life i think it's drag is proportional to sprite->vel square but not
 	// sure if that is worth the compute yet cause everythign else is shit)
-	if (sprite->vel.y > TERM_VELY) sprite->vel.y  -= (abs(sprite->vel.y)-TERM_VELY)/TERM_VELY_DIVISOR;
+	if (sprite->vel.y > TERM_VELY) sprite->vel.y   =  TERM_VELY;
 	if (sprite->vel.y < -TERM_VELY) sprite->vel.y += (abs(sprite->vel.y)-TERM_VELY)/TERM_VELY_DIVISOR;
-	if (sprite->vel.x > TERM_VELX) sprite->vel.x  -= (abs(sprite->vel.x)-TERM_VELX)/TERM_VELX_DIVISOR;
-	if (sprite->vel.x < -TERM_VELX) sprite->vel.x += (abs(sprite->vel.x)-TERM_VELX)/TERM_VELX_DIVISOR;
 
-	c = sprite_collision(map, sprite);
-
-	// don't let player move in a direction which they are already touching something
-	if (((c & SC_TL) | (c & SC_TR)) && (sprite->vel.y < 0)) { sprite->vel.y = 0; }
-	if (((c & SC_BL) | (c & SC_BR)) && (sprite->vel.y > 0)) {
-		// player jump
-		if ((joypad & J_A) && (sprite->frames_since_last_jump > JUMP_TIMEOUT_FRAMES)) {
+	int *offsets = sprite->collision_offset[sprite->bitmap_index];
+	// jump if on platform
+	if ((joypad & J_A) && (sprite->frames_since_last_jump > JUMP_TIMEOUT_FRAMES)) {
+		coly = map->data[GET_TILE_INDEX_BY_COORD(sprite->pos.x - offsets[0], sprite->pos.y - offsets[3]-LYO+1)];
+		if (!coly) coly += map->data[GET_TILE_INDEX_BY_COORD(sprite->pos.x - offsets[2], sprite->pos.y - offsets[3]-LYO+1)];
+		if(coly) {
 			sprite->vel.y = -JUMP_VEL;
 			sprite->frames_since_last_jump = 0;
 		}
-		else sprite->vel.y = 0;
 	}
-	if (((c & SC_RT) | (c & SC_RB)) && (sprite->vel.x > 0)) { sprite->vel.x = 0; }
-	if (((c & SC_LT) | (c & SC_LB)) && (sprite->vel.x < 0)) { sprite->vel.x = 0; }
-
-	int absvelx = abs(sprite->vel.x);
-	int absvely = abs(sprite->vel.y);
-	collision_check_steps =  (absvelx > absvely) ? absvelx : absvely;
 
 	original_position.x = sprite->pos.x;
 	original_position.y = sprite->pos.y;
 	// check if following the path by the velocity will lead to a collision
-	for (int step = collision_check_steps; step >= 0; step--) {
-		sprite->pos.x = original_position.x + ((step * sprite->vel.x)/collision_check_steps);
-		sprite->pos.y = original_position.y + ((step * sprite->vel.y)/collision_check_steps);
 
-		if (!sprite_internal_collision(map, sprite)) break;
+	// if no velocity component, pretend sprite has already collided
+	colx = sprite->vel.x == 0;
+	coly = sprite->vel.y == 0;
+
+	//for (int step = collision_check_steps; step >= 0; step--) {
+	if(sprite->vel.y != 0){
+		sprite->pos.y = original_position.y + sprite->vel.y;
+
+		if (sprite->vel.y < 0) {
+			coly += map->data[GET_TILE_INDEX_BY_COORD(sprite->pos.x - offsets[0], sprite->pos.y - offsets[1]-LYO)];
+			if (!coly) coly += map->data[GET_TILE_INDEX_BY_COORD(sprite->pos.x - offsets[2], sprite->pos.y - offsets[1]-LYO)];
+		} else if (sprite->vel.y > 0) {
+			coly += map->data[GET_TILE_INDEX_BY_COORD(sprite->pos.x - offsets[0], sprite->pos.y - offsets[3]-LYO)];
+			if (!coly) coly += map->data[GET_TILE_INDEX_BY_COORD(sprite->pos.x - offsets[2], sprite->pos.y - offsets[3]-LYO)];
+		}
+		
+		if (coly) sprite->pos.y = original_position.y;
 	}
+
+	if(sprite->vel.x != 0) {
+		sprite->pos.x = original_position.x + sprite->vel.x;
+
+		if (sprite->vel.x < 0) {
+			colx += map->data[GET_TILE_INDEX_BY_COORD(sprite->pos.x - offsets[0], sprite->pos.y - offsets[1]-LYO)];
+			if(!colx) colx += map->data[GET_TILE_INDEX_BY_COORD(sprite->pos.x - offsets[0], sprite->pos.y - offsets[3]-LYO)];
+		} else if (sprite->vel.x > 0) {
+			colx += map->data[GET_TILE_INDEX_BY_COORD(sprite->pos.x - offsets[2], sprite->pos.y - offsets[1]-LYO)];
+			if(!colx) colx += map->data[GET_TILE_INDEX_BY_COORD(sprite->pos.x - offsets[2], sprite->pos.y - offsets[3]-LYO)];
+		}
+
+		if (colx) sprite->pos.x = original_position.x;
+	}
+
+	sprite_update_bitmap(sprite);
+	sprite_draw_to_screen(sprite);
 }
 
-
-// calculate internal collisions
-unsigned int sprite_internal_collision(Map *map, Sprite *sprite)
+void sprite_update_bitmap(Sprite *sprite)
 {
-	unsigned int rv = 0;
-	SpriteCorners sc;
-	getSpriteCorners(sprite, &sc);
 
-	if (map->data[get_tile_index_by_coord(sc.itl.x, sc.itl.y)]) rv = rv | SC_ITL;
-	if (map->data[get_tile_index_by_coord(sc.itr.x, sc.itr.y)]) rv = rv | SC_ITR;
-	if (map->data[get_tile_index_by_coord(sc.ibl.x, sc.ibl.y)]) rv = rv | SC_IBL;
-	if (map->data[get_tile_index_by_coord(sc.ibr.x, sc.ibr.y)]) rv = rv | SC_IBR;
+	sprite->bitmap_index_prev = sprite->bitmap_index;
 
-	return rv;
+	     if ((sprite->vel.y > 0) && (sprite->vel.x > 0)) sprite->bitmap_index = SI_DOWN_RIGHT;
+	else if ((sprite->vel.y < 0) && (sprite->vel.x > 0)) sprite->bitmap_index = SI_UP_RIGHT;
+	else if ((sprite->vel.y > 0) && (sprite->vel.x < 0)) sprite->bitmap_index = SI_DOWN_LEFT;
+	else if ((sprite->vel.y < 0) && (sprite->vel.x < 0)) sprite->bitmap_index = SI_UP_LEFT;
+
+	else if ( sprite->vel.y < 0)                         sprite->bitmap_index = SI_UP;
+	else if ( sprite->vel.y > 0)                         sprite->bitmap_index = SI_DOWN;
+	else if ( sprite->vel.x > 0)                         sprite->bitmap_index = SI_RIGHT;
+	else if ( sprite->vel.x < 0)                         sprite->bitmap_index = SI_LEFT;
 }
 
-
-// check for external collisions (if rectangle is at least touchign something)
-unsigned int sprite_collision(Map *map, Sprite *sprite)
+void sprite_draw_to_screen(Sprite *sprite)
 {
-	unsigned int rv = 0;
-	SpriteCorners sc;
-	getSpriteCorners(sprite, &sc);
+	int bmi = sprite->bitmap_index;
 
-	// check if corners are in a non 0 tile
-	if (map->data[get_tile_index_by_coord(sc.itl.x,   sc.itl.y-1)]) rv = rv | SC_TL;
-	if (map->data[get_tile_index_by_coord(sc.itr.x,   sc.itr.y-1)]) rv = rv | SC_TR;
-	if (map->data[get_tile_index_by_coord(sc.ibl.x,   sc.ibl.y+1)]) rv = rv | SC_BL;
-	if (map->data[get_tile_index_by_coord(sc.ibr.x,   sc.ibr.y+1)]) rv = rv | SC_BR;
-	if (map->data[get_tile_index_by_coord(sc.itl.x-1, sc.itl.y  )]) rv = rv | SC_LT;
-	if (map->data[get_tile_index_by_coord(sc.ibl.x-1, sc.ibl.y  )]) rv = rv | SC_LB;
-	if (map->data[get_tile_index_by_coord(sc.itr.x+1, sc.itr.y  )]) rv = rv | SC_RT;
-	if (map->data[get_tile_index_by_coord(sc.ibr.x+1, sc.ibr.y  )]) rv = rv | SC_RB;
-
-	return rv;
+	if (sprite->bitmap_index_prev != bmi) {
+		set_sprite_tile(sprite->gb_sprite_index, sprite->bitmap_indexes[bmi]);
+		set_sprite_prop(sprite->gb_sprite_index, sprite->bitmap_prop[bmi]);
+	}
+	move_sprite(sprite->gb_sprite_index, sprite->pos.x, sprite->pos.y);
 }

src/sprite.h

@@ -4,17 +4,31 @@
 #include "./vec.h"
 #include "./map.h"
 
+typedef struct SpriteCorners {
+	UVec itl;
+	UVec itr;
+	UVec ibl;
+	UVec ibr;
+} SpriteCorners;
+
 typedef struct Sprites {
+	int gb_sprite_index;
 	int frames_since_last_dash;
 	int frames_since_last_jump;
-	int size;
+	int bitmap_index_prev;
+	int bitmap_index;
+	int bitmap_indexes[8];
+	int bitmap_prop[8];
+	int has_diag_sprites;
+	int has_joypad;
+	char name[20];
+	int collision_offset[8][12];
 	UVec pos;
 	Vec vel;
 	Vec acc;
 } Sprite;
 
 void sprite_iter_frame(Sprite *sprite, Map *map, int joypad, unsigned int *fc);
-unsigned int sprite_internal_collision(Map *map, Sprite *sprite);
-unsigned int sprite_collision(Map *map, Sprite *sprite);
+void sprite_draw_to_screen(Sprite *sprite);
 
 #endif